The purpose of this investigation is to study patients with various types of lipodystrophies and their family members, to determine the mode(s) of inheri- tance and to identify lipodystrophy-related candidate genes. Furthermore, the study will determine the natural course of the disease in patients with lipo- dystrophies through clinical and laboratory investigations. The study will attempt to answer the following specific questions: 1) Do the inheritance patterns of various forms of lipodystrophy differ? 2) What are the phenotypic variations in patients with various types of lipodystrophies? Do the relatives have milder varieties of lipodystrophy which may not be clinically apparent? 3) What are the peculiarities in the adipose tissue distribution in patients with various types of lipodystrophy? Are there other clinical differences in patients with various types of lipodystrophy? 4) Does the absence of fat from particular anatomical sites in different types of lipodystrophies influence glucose and fatty acid metabolism? 5) Does the absence of fat from particular anatomical site (or excess in other sites) affect lipoprotein lipase levels and thus, plasma tyiglyceride levels and chylomicron clearance? 6) What are the specific genetic defects in heritable forms of lipodystrophies?